The present invention relates to a developing device for use in an electrophotographic image forming apparatus such as a laser printer, copying machine, facsimile, etc., and more particularly, to a toner box structure which accommodates therein developing agents or toners.
In a conventional dry developing type, developing agents such as magnetic or non-magnetic toners are supplied to a developing region at a surface of a photosensitive drum for performing developing operation. Such type is described in a Japanese Patent Publication No. Hei 4-48232. In the disclosed device, a developing sleeve is housed in a developing case positioned in the vicinity of the photosensitive drum. The developing sleeve has an inner peripheral surface in which a magnetic roller is disposed and an outer peripheral surface on which the developing agents are carried. A toner box is provided detachably from the developing case so as to supply the developing agents from the toner box to the developing case.
A toner discharge port is formed in the toner box and a toner inlet port is formed in the developing case. These ports are aligned with each other when installing the toner box into the developing case. Further, a lid member which shuts off the toner discharge port and another lid member which shuts off the toner inlet port are provided. The toner discharge port and the toner inlet port are communicated with each other for the toner supply if these two lid members are aligned with each other and pulled out.
However, with the above structure, the two lid members are pulled linearly in a direction to project out of the bodies of the toner box and the developing case. Thus, the pulled out lid members are largely protruded laterally of the toner box and the developing case, which may be bulky. Further, since the inner surfaces of the lid members are attached with toner particles, the protruding lid members may contaminate the ambient components or portions.
Further, has been known an image recording apparatus such as a printer and a copying machine where a sheet cassette is provided detachable with respect to a main frame thereof. However, with the above structure, no specific relationship is provided between the operation for opening the lid member of the toner box and operation for installing the sheet cassette. As a result, if the lid is not open while the toner box is installed onto the developing case, i.e., if the image recording operation is started by supplying a sheet from the sheet cassette while the toner supply cannot be performed from the toner box to the developing case, toner shortage occurs in the developing case. Therefore, a desired imaging quality cannot be obtained. If the image recording operation continues while the toners are completely used up, the developing sleeve and the photosensitive drum may be damaged.
Furthermore, the attachment direction of the toner box with respect to the developing case is important. If the toner box is attached to the developing case in an erroneous attachment direction, the toner discharge port and the toner inlet port are misaligned from each other, so that opening and closing movement of the lid member which covers the toner discharge port of the toner box cannot be performed concurrently with the movement of the lid member which covers the toner inlet port of the developing case. Further, due to the misalignment with the ports, toners may be spilt outside.